An outbreak of diarrhea in a day care center is suspected to be of rotaviral origin. Which test is most appropriate to diagnose this outbreak?

EIA (b) is the best test for clinical diagnosis of rotavirus infection. Culture (a) is now possible but is not routinely done. Electron microscopy (c) detects rotavirus infection as well as other viruses that cause gastroenteritis, but EM is not routinely available for clinical diagnosis. Histologic examination of biopsy (d) would show characteristic changes in the small intestinecaused by rotavirus but the changes are similar to those caused by noroviruses; such an invasive test is unnecessary. Serology(e) is used for epidemiologic purposes only. See the table below for additional information.CHARACTERISTICS OF VIRUSESTHAT CAUSE GASTROENTERITISaFamilyReoviridaeCaliciviridaeAstroviridacAdenoviridaeVirusRotavirusNorovirus, SapovinisMamastrovirusMastadenovirusGenomebdsRNA(+) ssRNA(+) ssRNAdsDNASerotypes5More than 48 or more2 (40/41)EpidemicitySporadic, outbreak, epidemicEpidemic, outbreakSporadic, epidemicSporadicSeasonNov-AprSummer (ships)Peak in winterNoneRisk for clinical diseaseInfants <2years; all ages mildAdults; allagesInfant <2 years; all agesInfants; all agesIncubation period1-3 days12-48 hours1-28-10MajorsymptomsFever, vomiting, watery diarrhea, abdominal painVomiting, nausea, watery diarrhea, stomach pain, feverDiarrhea followed by nausea, vomiting, feverFever, watery diarrhea, vomitingDuration of symptoms 3-8 days24-72 hours3-4 days7-14 daysDiagnosisEIAEIAEMEIA